The present invention relates to an exhaust apparatus for a treatment unit for electrical components, preferably wafers, and, in particular, an exhaust apparatus for a spray tool to clean electrical components, whereby the particles located in the treatment unit are removed by suction. The invention furthermore relates to a system for treating electrical components. Finally, the invention also relates to a process for the removal by suction and/or rinsing of particles from a treatment unit of such a system.
The semiconductor industry frequently uses chemical spray tools to remove organic and inorganic contaminants from the very small chip structures that today have structural widths of 0.20 xcexcm. The wafers become contaminated, for example, during the treatment process, e.g., in the plasma etching process used to produce the microstructures or the like, where difficult-to-remove organic polymers are created. Furthermore, e.g. after photolithographic steps, the silicon wafers must be cleaned of coating residues, which may be accomplished by spray tools.
The spray tools generally contain a carrier for the wafers, which in turn is located within a sealed housing. The process chemicals or chemical mixtures required for cleaning are sprayed through spray nozzles from the top or from the side onto the wafer surface.
In addition to cleaning the wafer surfaces of organic and inorganic contaminants, the removal of particles, such as dust particles from the clean room, also plays an important role. With chip structure widths of less than 0.4 xcexcm, which are found, for instance, in the 16 MB DRAM chip, particles with a diameter greater than 0.16 xcexcm may result in component failure. To ensure that the treatment unit itself does not cause particle contamination requires monitoring for particles greater than 0.16 xcexcm diameter and their removal from the treatment unit.
Monitoring is not possible in conventional exhaust apparatuses for this type of spray tool, or treatment unit in general, which is made of polypropylene. Randomly occurring particle contamination frequently causes high defect densities on wafers and, not least of all, wafer reject rates, and thus results in production down time of the spray tool.
It is accordingly an object of the invention to provide an exhaust apparatus and method of operating an exhaust apparatus which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, in which comprehensive cleaning of the electrical components in the corresponding treatment units even if cleaning from particles as small as 0.16 xcexcm in diameter is required, is ensured.
With the foregoing and other objects in view there is provided, in accordance with the invention, an exhaust apparatus for a treatment unit for treating electrical components including wafers, the exhaust apparatus removing by at least one of suction and rinsing, particles located in the treatment unit, the exhaust apparatus containing:
a main exhaust pipe having an outside pipe and an inside pipe with a number of nozzles formed therein;
a side pipe having an outside pipe, an inside pipe with a number of nozzles formed therein, a first end to be connected to the treatment unit, and a second end connected to the main exhaust pipe; and
a storage tank containing a cleaning fluid connected to the inside pipe of the main exhaust pipe and the inside pipe of the side pipe such that the cleaning fluid at least intermittently flows through the inside pipe of the main exhaust pipe and the inside pipe of the side pipe.
According to a first aspect of the invention, the object is attained in that the exhaust apparatus serves to remove particles located in the treatment unit by suction. According to the invention, the exhaust apparatus contains the main exhaust pipe that is provided with an outside pipe and an inside pipe, with the inside pipe having a number of nozzles, and the side pipe that connects the treatment unit with the main exhaust pipe and is provided with an outside pipe and an inside pipe, with the inside pipe having a number of nozzles. The inside pipes are connected with a source for cleaning fluid so that a cleaning fluid at least intermittently flows through the inside pipes.
The exhaust apparatus according to the invention permits monitoring and removal by suction of particles greater than or equal to 0.16 xcexcm in diameter so that particle contamination of the treatment unit and the electrical components with the aforementioned disadvantages is prevented.
The cleaning fluid is injected into the main exhaust pipe and the side pipe through the nozzles of the inside pipes so that these pipes can be rinsed with the cleaning fluid. This prevents contamination of the electrical components with particles originating from the exhaust apparatus. The inside pipes are suitably connected with the source of the cleaning fluid, which is stored in a suitable tank, for example, by corresponding lines.
Rinsing or cleaning is advantageously conducted after completion of a treatment process in the treatment unit and will be described in further detail below.
Application of the exhaust apparatus according to the invention is not limited to specific treatment units. Rather, it may be used wherever electrical components are sprayed with materials and where such spray materials must be subsequently removed by suction. An advantageous example is the application of the exhaust apparatus in a spray tool for cleaning wafers.
According to the invention, the side pipe can have an outside pipe with a 90 mm diameter and/or an inside pipe with a 20 mm diameter. The invention is of course not limited to the above diameters.
In a further embodiment, the side pipe can be formed of two or more partial areas. The partial areas are advantageously aligned at an angle with respect to each other. The angled embodiment of the side pipe further reduces the risk of particles entering the treatment unit from the side pipe. The angled side pipe can be configured as one piece or several pieces. In the latter case, the individual partial areas are produced first and are then assembled into the side pipe.
The partial areas are preferably aligned with respect to each other at an angle of between 135xc2x0 and 155xc2x0, preferably between 140xc2x0 and 145xc2x0, particularly at an angle of 142xc2x0 30xe2x80x2.
According to the invention, at least one of the edge-side partial areas of the side pipe may be connected with an extension element. Using one or several of the extension elements makes it possible to take into account the structural conditions, including the different distances between the treatment unit and the main exhaust pipe. If an extension element is used, the inside pipe is preferably also extended so that the extension element can also be rinsed with the cleaning fluid.
In a further embodiment, the main pipe is provided with an inside pipe with a diameter of 25 mm. Here, too, the diameter can be varied as required.
The pressure of the gas phase within the main exhaust pipe is preferably set within a range of 2.03 cm (0.8 inches) to 4.3 cm (1.7 inches)/water column, preferably at 3.81 cm (1.5 inches)/water column.
The main exhaust pipe and the side pipe are preferably connected with each other at an angle of 25xc2x0 to 40xc2x0, preferably 30xc2x0. This angled configuration is important for the exhaust apparatus according to the invention, since it further improves the cleaning effect and prevents particle contamination.
In a further embodiment, the main exhaust pipe is connected with an additional exhaust pipe, whereby the exhaust pipe is connected or connectable with a clean room. The additional exhaust pipe is used to draw in air for the suction process within the exhaust apparatus. Drawing air out of the clean room, which has the result that the air quality is that of clean room Class 1 or better, ensures that no particles can be diffused back into the exhaust apparatus through the exhaust pipe. Furthermore, intake of clean room air via the exhaust pipe has the purpose of equalizing the pressure of the cleaning fluid within the main exhaust pipe.
According to the invention, the main exhaust pipe may be connected with a gas scrubber. The gas scrubber, kept under a constant flow of, for example, 5 liters/minute of cleaning fluid, prevents acid or basic gases from being released into the environment. Furthermore, it protects the treatment unit from any back flow of particles from the ventilation system of the exhaust apparatus.
In a further embodiment, the nozzles within the inside pipe can be spaced 5 to 20 cm apart. The appropriate distance between the nozzles is a function of the diameter of the side pipe and the main exhaust pipe as well as of the amount of cleaning fluid required for full rinsing of the pipes.
Advantageously, 10 to 15, preferably 11 nozzles can be disposed in each of the inside pipes. Depending on the requirements, e.g., if an extension element or similar is used, a different number of nozzles may be appropriate.
According to the invention, the nozzles can have 1 to 10 nozzle openings that are preferably formed across the circumference of the inside pipe. The nozzle openings can have a diameter of, for example, 0.3 mm to 1.0 mm. Preferred nozzle opening diameters range from 0.5 mm to 0.7 mm. The selected diameter of the nozzle openings depends, among other things, on the number of nozzle openings per nozzle. In a preferred embodiment, for example, 1, 3 or 10 nozzle openings per nozzle can be provided. The number of nozzle openings depends, in particular, on the geometry of the pipes to be rinsed as well as on the areas of the pipes that are to be reached by the cleaning fluid. 10 nozzle openings distributed at a single position of the inside pipe over the entire pipe circumference at that location permit uniform rinsing of, for example, the side pipe or the main exhaust pipe over its entire cross section.
In a further embodiment, the side pipe and/or the exhaust pipe can be made of PVDF plastic (polyvinylidene fluoride) or another chemically inert plastic. This special material further reduces possible particle contamination.
The main exhaust pipe can advantageously be made of PVC plastic (polyvinyl chloride) or some other plastic. In particular, the main exhaust pipe can also be made of PVDF plastic.
According to the invention, the cleaning fluid may be DI water (deionized or demineralized water). The use of DI water provided with wetting agent compositions is also advantageous. Depending on the application, other cleaning fluids with specific chemical compositions may be used.
According to a second aspect of the present invention, a system is provided for treating electrical components, preferably wafers, with at least one treatment unit for treating the electrical components, particularly the spray tool for cleaning the electrical components, and with an exhaust apparatus according to the invention as described above.
With such a system, the electrical components can be cleaned in a simple manner sufficiently thoroughly that contamination with particles greater than or equal to 0.16 xcexcm in diameter is almost completely prevented, particularly limited to a maximum of ten additional particles on 200 mm wafers. This makes it possible substantially to reduce the reject rates of the electrical components as well as any downtimes of the system.
In principle, the system according to the invention can be used to treat any type of electrical component. However, the system is preferably used to treat microelectronic components, wafers or the like.
One or several treatment units, connected with the same or with different exhaust apparatuses, may be provided per system.
Since the specially configured exhaust apparatus is an essential feature of the system, full reference is herewith made to the above statements regarding the exhaust apparatus with respect to the advantages, actions, effects and mode of operation of the system according to the invention.
According to the invention, the treatment unit can be disposed within a clean room, while the exhaust apparatus can be disposed outside the clean room. This allows the clean room to be kept as small as possible. It also permits any work on the exhaust apparatus to be carried out without contaminating the atmosphere of the clean room. Of course, the exhaust apparatus can also be disposed within the clean room with appropriate clean room protective measures.
In a further embodiment, the main exhaust pipe of the exhaust apparatus is connected with the clean room via the exhaust pipe resulting in the aforementioned advantageous effects.
According to the invention, the main exhaust pipe can be connected to a chimney. Through the chimney, the particles that are removed by suction from the treatment unit can be released to the outside. To prevent harmful gases from being released into the environment, the main exhaust pipe is preferably connected to the chimney via the gas scrubber.
Advantageously, each of the treatment units is directly connected with the chimney via an additional, separate exhaust. This makes it possible to prevent even more completely any particle back flow into the treatment chamber of the treatment unit.
In a further embodiment, a motor may be provided to support the suction process. This motor, which may be set, for example, at 8 m/second, regulates the exhaust flow from the side pipe and the main exhaust pipe to the chimney.
According to the invention, the system can be used to clean wafers, particularly to clean wafers from particles greater than or equal to 0.16 xcexcm.
The exhaust apparatus according to the invention as well as the system according to the invention are particularly suitable for hot chemical processes, for example, the removal of photoresist residue with concentrated sulfuric acid mixtures, during which spray chamber temperatures in excess of 100xc2x0 C. occur and result in the corrosion of plastic parts. Furthermore, the exhaust apparatus is excellently suited for processes where particles are created in the gas phase by a chemical reaction, for example, salt formation, which would contaminate the electrical components, such as wafers, through back flow. The exhaust apparatus and the system are also particularly suitable for processes using ammonia and hydrochloric acid (SC1/SC2 processes) to clean semiconductor structures from organic and inorganic contamination.
According to a third aspect of the present invention, a process is provided for the removal by suction and/or rinsing of particles from a treatment unit of a system to treat electrical components, preferably wafers, as described above, using an exhaust apparatus as described above, which according to the invention is characterized by the following steps:
a) removing particles by suction from the treatment unit during the treatment process via the side pipe into the main exhaust pipe and guiding the removed particles to the chimney, preferably via the gas scrubber, whereby air from the clean room is drawn via the exhaust pipe into the main exhaust pipe to support the suction process;
b) after completion of the treatment process, piping cleaning fluid into the inside pipes of the side pipe and the main exhaust pipe and injecting the cleaning fluid via the corresponding nozzles into the side pipe and the main exhaust pipe to rinse them; and
c) discharging the cleaning fluid from the side pipe and the main exhaust pipe after completion of the rinsing process.
The process according to the invention permits cleaning of the electrical components and the treatment unit without the aforementioned contamination of the electrical components. Full reference is herewith again made to the above statements regarding the embodiments of the exhaust apparatus and the system with respect to the advantages, actions, effects and the mode of operation of the process.
At the end of a treatment cycle, the entire exhaust apparatus is flooded with cleaning fluid. This fact as well as the special embodiment of the exhaust apparatus and the system makes it possible to minimize contamination with particles greater than or equal to 0.16 xcexcm.
The cleaning fluid used for cleaning can be discharged directly into an effluent channel located underneath the treatment unit.
Advantageously, rinsing of the side pipe and the main exhaust pipe can be accomplished over a period of 0.5 to 10 minutes, preferably 2 minutes. For extreme processes, continuous rinsing is also feasible.
According to the invention, the rinsing operation of the exhaust apparatus can be triggered by opening the cover in the treatment unit. This ensures that rinsing and cleaning start automatically and immediately after completion of the treatment process in the treatment unit.
To avoid contamination of the products by electrostatic charging of the plastic used in the system, the electrostatic charges may be compensated by using electrostatic deionizers for 1 to 5 minutes (ideally 2 minutes) at the end of each cleaning run. Depending on the spray tool or the treatment unit, 5 to 20 deionizers may be provided, which are disposed 1 to 20 cm apart from one another, preferably 10 cm apart, at a height of 0.5 to 5 m, preferably 1.5 m, above the chamber of the treatment unit. Deionization takes place automatically after the cover of the treatment unit has been opened. Subsequently, a countdown occurs, which gives the operator or an automatic unloading system the green light to unload the treatment unit after the deionization period has been completed.
Advantageously, the pressure of the gas phase in the main exhaust pipe is set at 2.03 cm (0.8 inches) to 4.4 cm (1.7 inches)/water column, preferably to 3.81 cm (1.5 inches/water column.
According to the invention, the gas scrubber can be kept under a constant flow of cleaning fluid at 5 liters/minute.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an exhaust apparatus and method of operating the exhaust apparatus, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.